Personal computer systems in general, and IBM Personal Computers in particular, have obtained widespread use for providing computer power to many segments of today's modern society. Personal computer systems are usually defined as a desk top, floor standing, or portable microcomputer that includes a system unit having a system processor, a display monitor, a default personal computer (PC) keyboard, a mouse, one or more diskette drives, a fixed disk storage, and an optional printer. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. These systems are designed primarily to give independent computing power to a single user and are inexpensively priced for purchase by individuals or small businesses. Examples of such personal computer systems are IBM's Personal Computer AT and IBM's Personal System/2 Models 25, 30, 50, 60, 70 and 80.
New uses for personal computer systems have rapidly developed due to improved performance and capabilities of new microprocessors and the availability of multi-tasking operating systems. Personal computers are now commonly used as file servers, print servers, network nodes, and in other applications that require the simultaneous support of multiple users. This type of operation, called server mode, is usually associated with a personal computer system having a plurality of high volume mass storage devices for holding a database for a small business or a corporate department. These servers typically run independently of an operator and are usually connected by a local area network (LAN) to other personal computers whose users need to access the database information.
It should be appreciated that independent operation of the server is a substantial factor in achieving marketable success of these machines. As mentioned previously, a normally configured personal computer has required a PC keyboard and display to be an integral part of the personal computer system at all times. With the increasing usage of servers and other factors, there is now a requirement that the personal computer system be capable of being operated with either; a traditional PC keyboard, a traditional display, or an ASCII terminal connected to a communications port or with no keyboard, no display, or no terminal.
However, the requirement that a computer system be capable of being operated without a traditional PC keyboard or display causes problems with diagnostic software procedures which have been permanently built into these types of personal computer systems. In particular, when IBM first began shipping the IBM PC in 1981, it included diagnostic features that were generally not available before in personal computers. These diagnostic features were incorporated into a power on self test routine commonly referred to as POST. The POST is composed of diagnostic routines or modules contained in a planar ROM firmware that test all the main system components at power on time. Whenever the computer is started up or reset, POST automatically performs a series of tests that check various components in the system. The components tested by this procedure were deemed to be primary items critical to the operation of the system. Primary items included the CPU, ROM, planar support circuitry, memory, PC keyboard, display, and major peripherals such as a floppy or fixed disk. Although these tests were brief and not as thorough as with other disk-based diagnostics that were available; the POST process provided error or warning messages whenever a major faulty component was encountered. Two types of messages were usually provided: first an audio code and second a display screen message or code. If an error was detected during the POST procedure an error message was displayed or an audio message was sounded. These messages were and still are normally in the form of a numeric code several digits long. For example, the numeric code of 301 on the display can indicate that the PC keyboard is not connected to the system.
As is readily apparent, two of the major components that are tested during the POST process are the PC keyboard and display. As mentioned before, if a PC keyboard is not connected to the system or malfunctions, a 301 numeric message is indicated on the display. The user is then requested to enter the "F1" key to continue. As is apparent, the absence of the PC keyboard negates the user entering the "F1", an unworkable situation.
With the advent of servers which normally do not need to operate with a keyboard or display, problems occur with POST halting the computer in the absence of the keyboard or display when in actuality the server is designed to run in this configuration. It has therefore become necessary to provide an optional keyboard.